Two rangemasters, one box...

Discussion in 'Burnt Fingers DIY Effects' started by bendeane, Mar 31, 2013.

  1. bendeane

    bendeane Tele-Meister

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    Okay, so not a rangemaster to 100% specs, but here's the deal...

    I was given an old Direct Box that was broken and decided to use that as the enclosure for my first DIY pedal, a rangemaster simple enough to boost my confidence in building this stuff. Well, I don't have all the right parts to make this germanium transistor based (I'm really just missing a good germanium transistor and will probably snag one of ebay.

    I got some stripboard from Tayda (man there stuff is reasonably priced) and enough caps and resistors to build two circuits plus some extra resistors 'cause they were so cheap.

    Well, I finished the board with a silicon Radio Shack and it's a pretty small board. I have a DPDT two way switch laying around and though I could build the same circuit again only use a germanium OC44 and wire it up so that the switch basically switches between the two identical circuit other than the transistor.

    More for practice soldering, laying out clean stripboards and just to see if I can do it, but I thought it would also be a good experiment to have a boost pedal based on a silicon transistor and germanium just to get a good A/B of the two and to see which one I like better and which one my more experienced and tone savvy guitar friends like (kind of like a blind taste test).

    Anyway, taking the old direct box to dad's today to have him help me drill a few extra holes and then just waiting on the germanium transistor. Maybe I'll post some sound clips if I get that ambitious, but I'll at least show pictures.

    Heck, with the size of the box, I could probably fit another board in there, but I just had a thought to try and add that 6 way switch mod I've seen with different capacitors that would dictate what frequencies got boosted.
     
  2. bendeane

    bendeane Tele-Meister

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    Okay, so thinking about this a little more and have a question. Can I send both circuits to the same pot? My first assumption is I don't see why not, but wanted some feedback on the issue.
     
  3. tjk3052

    tjk3052 Tele-Holic

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    Be careful with the type of transistors you're using. OC44 is PNP and will need reverse polarity power. You could use a PNP silicon and use a positive ground, or an NPN germanium and a negative ground, but don't mix the 2 types.

    You might be able to share the pot if one of the circuits is bypassed. Post a schem of what you're thinking. If you're new to this, though, I would keep it simple and build them separate first. Once they're working and you get them tweaked to your liking you can try all sorts of clever things.

    Have you read through this yet? http://www.geofex.com/article_folders/rangemaster/atboost.pdf
     
  4. jefrs

    jefrs Doctor of Teleocity

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    Provided you test the device is ok, I don't see why you cannot use is as a form of mixer - two inputs into one output. A lot of mixers do just that, have a buffer amp feeding a resistive mixer (several resistors join at one point into the input of the amp proper).
    I'm assuming you are sticking fairly close to the one transistor Rangemaster circuit which does have an output resistor.

    Btw you /can/ mix pnp and npn provided one is inverted, probably not in a Rangemaster though, but there are applications for this.

    You can swap silicon for germanium but what you cannot do is simply substitute npn for pnp.
    The original Rangemaster was pnp germanium but no reason you cannot build a npn silicon version. You have to tweak a few values depending on which transistor is actually used.
     
  5. bendeane

    bendeane Tele-Meister

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    PNP all the way...

    My initial build when getting into all this was silicon PNP. I just went with what I could find fastest for the rangemaster just to see if I could get the circuit working. Silicon PNPs in a mixed bag at radio shack. I here a lot of people going on and on about hfe and germanium and how silicon wont' sound as good and you want the hfe around 70-90, but these are rated for 200 hfe and are silicon and I think the thing sounds fine. It sounds like a pretty good representation of the guitar just boosted. It really drives my amp well (maybe it is just that I have a really good amp (Rivera Jake 112 combo)).

    So both circuits are positive ground, but I appreciate the info, regardless.

    I am wondering about the pot, because if I run the leads to the pot lugs from both circuits into the same pot, will I be "connecting" the two circuits? I'll post the schematic in a bit after I finish up some other work stuff.
     
  6. bendeane

    bendeane Tele-Meister

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    Layout

    Okay, so here's my layout. As I was doing this, a few other questions besides two circuits sharing the same volume pot. First, can I power both circuits of the same battery? If the 3pdt switch is the footswitch that basically bypasses the circuit, the third pole for LED, which I don't need to draw out in my layout, and the DPDT switch would basically switch between each circuit.

    I'm assuming I can just "double tap" the battery, so to speak, but just wanna make sure that won't either A)reduce battery life a little faster because the battery would be powering both circuits at the same time and B)connect the circuits in such a way that this idea won't work.

    Suggestions or confirmations that this will work?

    Thanks,
    Ben
     

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  7. bendeane

    bendeane Tele-Meister

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    Continued thinking...4PDT anyone?

    Okay, so I keep running this circuit through in my head and I think instead of a DPDT switch to switch circuits, I need a 4PDT switch. I can take the output cap out of the picture and just use one cap for both circuits. Send lug 2 of the pot to the cap and then to the output. Send the other two lugs of the pot to the 4PDT switch and the two different leads from each circuit to the respective lugs on the 4PDT switch to make this work.

    Any opinions or thoughts on the matter?
     

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  8. poiureza

    poiureza Tele-Holic

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    My head is spinning from those hookups.
    Are you sure you want to make it that complex for a first build ?
    There is a zillion things that can go wrong.

    If anything, my impression is that if you don't fully separate both circuits, the one being "off" might still modify your tone (cfr my posts on Suede's thread)
     
  9. bendeane

    bendeane Tele-Meister

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    It does look overwhelming, but once I got my heads around it, it seemed to become a little simpler. Of course, the layout software isn't what I like to spend a ton of time with making look clean so all those leads look a little messy to me in that drawing. I already have the silicon circuit wired and working and I just have quite a bit of empty space in the enclosure that I figured, what the heck, it's all about learning.

    The output cap is completely independent when I use a 4pdt switch. There is no way it can "connect" the two circuits together when using that switch.

    One pole switches between the input of each circuit, the next pole switches the outputs and the last two poles switch the circuits leads to pot lugs 1 & 3 respectively.

    I really just want to see if I can do it. I don't have a ton invested in parts. I found a place called Tayda electronics and they have great prices. I think I spent 8 bucks with shipping to get enough parts to build 10 of these circuits with different transistors if I wanted to. I'm really just a pedal junkie trying to learn how to do this myself.
     
  10. Meshgearfox

    Meshgearfox Tele-Meister

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    Why not just make two independent circuits with their own pots and 3pdt switches? Put them in the same case and share the battery/ power supply if you want, but with independent pots you could have two different boost tones available and with both of them on you might find some interesting distortion/ fuzz tones.

    That said, I don't see why the 4pdt version wouldn't work. The biggest problem is that the pot setting that sounds best with the transistor version probably wont be optimal for the germanium, so you'll be bending over to twist the knob every time you switch between them.
     
  11. jefrs

    jefrs Doctor of Teleocity

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    No, I'm sorry, I cannot understand these schematic layout things, can you draw a proper circuit diagram?

    The circuit diagram serves two purposes, it shows what you are proposing, and it shows how it will work. I'd have to reverse-engineer your pretty pics to figure it out.
     
  12. bendeane

    bendeane Tele-Meister

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    Thanks for saying my pics look pretty. I'll double up two rangemaster schematics and see if I can't add the switches to the schematics.

    I feel like I'm leaning toward mesh's idea though.

    I've already drilled for a mini toggle, on pot and one 3pdt footswitch. I think I may finish this one with just the single circuit and maybe use the toggle to switch between two different input capacitor values to change what frequencies are boosted.

    Then into the two circuit version with independent pots and switches.
    Then I'll probably do a third with the 6 way rotary switch I've seen with different cap values.
    But don't let me get to ahead of myself. It's all good soldering practice.
     
  13. jefrs

    jefrs Doctor of Teleocity

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    This is a circuit diagram
    [​IMG]

    This is the npn version
    [​IMG]
    With a circuit diagram as opposed to a component layout, we can figure out what the electronic circuit is doing.

    If you are using either of those circuits then I suggest running the outputs through a ~10k before joining them to separate the two circuits.
     
  14. bendeane

    bendeane Tele-Meister

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    I'm using basically the first. The box for small really fast between the pot, board and wires. It's not as deep as it seemed so I ran out of space pretty quick. Works though and sounds good.
     
  15. steve440

    steve440 Tele-Meister

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    I think your circuit would work but it looks like a bit of a mission;) Also 4pdt are really expensive:( Why can't you just have a 2pdt switching the box on and off, then a 2pdt switching between the 2 circuits? Use 3pdt if you want the led's. I'd also put a range pot on the front of each circuit to adjust the input cap. Maybe swap the 4k7 on the emmiter to a 10k trim so you can bias it up easier.

    Steve
     
  16. bendeane

    bendeane Tele-Meister

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    I've heard all these people talking about how expensive 4pdt switches are. Tayda electronics sells 4pdt stomp switches for $4.49 and small bear sells 4pdt mini toggles for about 4 bucks.
     
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